Defining A Healthy Riparian Area

Dr. Karl Wood, DirectorWater Resources Research Institute

Dr. Terrell Baker, Riparian EcologistNew Mexico State University

Las Cruces, NM

Webster’s Definition of “Health”

1. Physical and mental well-being;

2. Soundness;

3. Freedom from defect, pain, or disease;

4. Normality of mental and physical functions

How does this definition apply to riparian areas?

What are some other terms or phrases used to describe watersheds?

Sustainable

Functioning and Non-Functioning

Proper Functioning Condition

Impaired

Stable

Upward Trend

At Risk

Downward Trend

Rangeland Health (Natural Research Council 1994)“The degree to which the integrity of the soil and ecological processes of rangeland ecosystems are maintained”

Forest Health (U.S. Forest Service)“A condition wherein a forest has the capacity across the landscape for renewal, for recovery from a wide range of disturbances, and for retention of ecological resiliency, while meeting current and future needs of people for desired levels of values, uses, products, and services”

Some Related Definitions

Riparian Health (Need Citation)“” Feds have some 70 plus definitions

Compare to Wetlands

• Lots of science

• Tight definition (at least comparatively)

• Regulatory authority

1. They convey that everything is either right or wrong.

2. They infer that nature gives values to society.

3. They also infer that society’s values are mutual across all lands,

both public and private

Why this vision of everything being black or white,

and why are these definitions bothersome?

Most people have an intuitive idea of what constitutes a healthy riparian area; at least, they believe they can recognize an unhealthy one

when they see it.

Using “health” to describe watersheds is probably inappropriate.

Riparian Conditions Fall Along

A Continuum!

How can we express that continuum?

Ecosystem Succession or the Sere is a good start!

Concept of the Sere

Bare Rock

LichensMosses

Soil depth and richness

ClimateAnnuals

Perennial grasses and forbsShrubs

Deciduous trees

Conifers Climax

Time

Example developed in North America by H.C. Cowles and F.E. Clements about 100 years ago

Conifer invasionof a meadow

Early ponderosa pine savanna

Ponderosa pine thicket today

Insects and disease spread in a crowded forest

Concept of the Sere

Bare Rock

LichensMosses

Soil depth and richness

ClimateAnnuals

Perennial grasses and forbsShrubs Climax

Time

Concept of the Sere

Bare Rock

LichensMosses

Soil depth and richness

ClimateAnnuals

Perennial grasses and forbs Climax

Time

Concept of the Sere

Bare Rock

Lichens

Soil depth and richness

Climate

Climax

Time

Would A Society Ever Want To Maintain Bare Rock

Or a Very Low Seral StageRiparian Area?

Example: Irrigation Ditches

• The kinds of animals different in each seral stage.

• The climax seral stage usually does not represent the greatest species diversity of plants and animals.

• Subclimax seral stages may be maintained by continuous or discontinuous perturbations such as fire, grazing, hurricanes, etc.

• Movement towards climax is called succession

• Movement away from climax is called retrogression (e.g. Desertification)

• Multiple equilibrium communities and complex successional pathways may be possible within a sere.

General Comments On Ecosystem Succession

Explanations of “ecosystem succession” have been modified and expanded by:

Gleason 1926 – recognized individual species differencesTansley 1935 – proposed more than one climax for a siteWatt 1947 - identified the importance of patches and disturbance cyclesEgler 1954 – noted that species did not always invade but were present and

increased Pickett 1976 – recognized importance of natural selection and disturbanceConnell and Slatyer 1977 – proposed facilitation, tolerance, and inhibitionGrime 1979 – proposed ruderal, competitive, and stress-tolerant stagesHuston and Smith 1987 – demonstrate 5 successional patterns: sequential succession, divergence, total suppression, convergence, and pseudo-cyclic replacementShugart 1984 – claimed mechanistic rather than deterministic processesWestoby 1989 – explained state-and-transition models or thresholdsOliver and Larson 1990 – allowed for chaotic or non-equilibrium cycles

To manage a riparian area, managers need to know:

1. What is the potential or climax seral stage of the riparian area?

2. What is the present seral stage of the riparian area?

• Is it all the same or are there different seral stages in different parts of the riparian area?

4. Can the preferred seral stage be achieved with the present technology, time, legal, political, and economic constraints?

3. Are there several acceptable seral stages and a preferred seral stage of the riparian area

and/or its parts?

Concept of the Sere

Bare Rock

LichensMosses

Soil depth and richness

ClimateAnnuals

Perennial grasses and forbsShrubs

Deciduous trees

Conifers

Time

Mostchoicesare here!

If on the other hand the prime objective is watersheds, we should restore grass, which all the evidence indicates is a better watershed cover than either brush or woodland.”

Aldo Leopold

“If the prime objective is wood products, we may continue to overgraze, letting in the woodland and sacrificing watershed values.

Steps for Watershed Management

Preliminary Assessment and Surveillance

Preliminary Assessments and Surveillance

“Nothing in nature is isolated. Nothing is without reference to something else. Nothing achieves meaning apart from that which neighbors it.”

Johann Wolfgang von Goethe

“There is something fascinating about studies of science. One gets such wholesale returns of conjecture out of such trifling investment of fact.”

Mark Twain

Steps for Watershed Management

Preliminary Assessment and Surveillance

Goal Setting

Prioritization and Targeting

Watershed Planning – develop document with roles and implementation strategy

Implementation

Performance evaluation

For any given response variable such as: Erosion, Runoff, Evaporation,

Stream Temperature, Sediment Load, Arsenic Content, Plant Growth, Insect Populations, etc.

Questions should be asked:1. What are the natural levels with variations between hours,

days, months, and years?

2. What are maximum potential levels?

3. What are the tolerable levels to sustain the preferred seral stage?

4. What are the desirable levels?

5. Are the desirable levels achievable with present technology, time, legal, political, and economic constraints?

Nature abhors a void

Nature abhors topographical prominence

Nature abhors a crowd

Natural changes are often dynamic and catastrophic with unpleasant consequences for humans

Human changes of nature may be dynamic and catastrophic, or static, controlled, predictable, and

beneficial to humans, wildlife, and watersheds

Human influence is most probable for avoiding catastrophes and assuring ecological,

social, and economic stability.

Conclusions

A Healthy Watershed = preferred seral state is attained

Sustainability = preferred seral stage is maintained against the processes of succession and

retrogression, including invasions, especially by exotics

Conclusions

God bless America!

Thank you!

Thank you!